The Testoderm Study is a Phase I study of a transdermal patch containing the male hormone, testosterone, in 12 HIV-positive and 12 HIV-negative males, who are hypogonadal by measurement of serum testosterone. The study is designed to measure the serum testosterone at baseline, and at the end of a 28 day time period during which participants wear the transdermal patch. A second part of the study measures serum testosterone after another 28 days of medication usage. The drug is given as a transdermal patch worn on the scrotum, and changed daily. The first 2 days of the study (baseline and day one of therapy) are spent as an inpatient in the GCRC, during which time a careful physical examination is performed, and 12 blood samples are obtained. Patients are then instructed in use of the patches and sent home for self-administration. Patients return to clinic on days 7, 14 and 21 for more blood tests. Patients are again admitted to the GCRC on day 27 of the study, for urine and blood testing (16 blood samples). A quality of life questionnaire is filled out at both the first and the second GCRC inpatient stay. Clinic evaluations, consisting of a brief evaluation and blood sampling, occur in the outpatient clinic on days 42 and 56. On day 56, the final day of the study, a physical exam is also performed. The study's significance lies in the fact that testosterone, unlike other hormonal manipulations and patient-independent nutrition (e.g., TPN), adds lean body mass to HIV-infected and wasted patients, rather than fat. This is important as we become aware of the need to address the dysfunctional metabolism that studies have now shown to be common in advanced HIV-infection and AIDS. In addition, testosterone appears to contribute to an increased sense of well-being.